Photographic objective.



C. G. MINOR. PHOTOGRAPHIC OBJECTIVE.

APPLICATION FILED JUNE 7, 1912.

1,098,823, Patented June 2, 1914.

71 7727 esses: [n venfon- Orr: 2161 UNITED STATES PATENT OFFICE.

CHARLES C. MINOR, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-EIGHTH TO WIRT F. SMITH AN D ONE-FOURTH TO CHARLES L. J ENNESS, BOTH OF CHICAGO, ILLINOIS.

PHOTOGRAPHIC OBJECTIVE.

Specification of Letters Patent. Patented J 2 1914 Original application flied May 26, 1910, Serial No. 563,595. Divided and this application filed June 7,

1912. SerialNo 702,254.

signed for photographic purposes, and is related to the type of objectives shown and described in my application filed May 26, 1910,

Patent No. 1,077,420.

In the present invention, the lens system is shown as consisting on one side of the diaphragm of a meniscus lens, and on the tion of a. cemented flint lens L other side of the diaphragm of a plurality of lenses forming between them air spaces of plus meniscus form; the remaining element of the lens system being a lens of plus meniscus form placed at either end of the lens system. As shown in the drawing, the last mentioned lens L is placed in front of the meniscus lens L of the front combination constituting therewith a combination of two meniscus lenses curved in the same direction with an intervening air space therebetween. For gaining furthermore truer chromatic corrections, the inner one of these two lenses is achromatized, or if need be over-corrected chromatically, by the addi- The rear combination consists of two positive elements L and L and two negative elements L and L two of these elements, one positive and one negative, being cemented together; the other elements are provided with facing surfaces havin radii diiferin from the radii of the surfaces of the a jacent elements, so that air spaces A and B ofplus meniscus form curved in the same direction intervene therebetween.

From the construction above described, distinct and important advantages are gained. It is possible to secure a high relative aperture equaling about f 1.7 with practically the entire image field anastigmatically flattened, as well as to gain an exceptionally high degree of spherical correction and freedom from coma. There is also gained the much desired telephoto effect through causing the nodal point to lie in front of the front combination. There are many advantages gained by such a construction, the importance of which is obvious in the practical use of very rapid photographic lenses.

As is well known the image of a telephoto lens being considerably magnified over and above the size of an image given by any normal lens of the same size and distance from the focusing screen, the illumination is not only undiminished, but the depth of focus or rather depth of field is greatly increased, because of the fact that this results from a comparatively short focus lens systom. In the present invention this result is accomplished by shortening as far as possible the focus of the first mentioned element in front, and, also by lengthening the focal power of the next or cemented lens, or better still by giving it a decided minus focal power, and lastly by causing the focus of the back combination taken as a whole to be fromthree or four times that of the front combination, to a focus equal to zero or of minus focal power.

In the lens system described, the kinds of glass which may be used are almost without limitation.

I claim:

1. A photographic objective in which one component thereof consists of two meniscus lenses having two facing surfaces, one of said lenses having a cemented surface, and the other component of which comprises a plurality of lenses having two pairs of facing surfaces and one cemented surface, the radii of each of said pairs of facing surfaces being difi'erent so as to form air spaces of plus meniscus form, said airspaces being curved in the same direction.

2. In a photographic doublet having the nodal point thereof without the lens system, the front combination consisting of two lenses of meniscus form separated by an air space, one of the said lenses consisting of a crown and flint element cemented together, and the rear combination consisting of a. plurality of lenses separated from each other by at least two air spaces of plus meniscus form, the focus of said rear combination being from three times the focus of the front combination to a focus equal to zero or minus.

3. In a photographic doublet having the nodal point thereof without the lens system, the front combination consisting of two lenses of meniscus form separated by an air times the focus of the front combination'to space, one saideilllses being oger-correctecl a focus equal to zero or minus.

chromatica y, an t erear com ination consisting of a plurality of lenses separated CHARLES MINOR 5 from eachother by at least two air spaces of Witnesses:

plus meniscus form the focus of said rear EPHRAI BANNLNG,

combination being trom substantially three CHARLES L. JENNESS. I 

